Posted by Sandy on Saturday, March 31, 2012 at 2:07pm.
What is the domain of
f(x) = √(x^22x8)
Thanks!

Math  Bosnian, Saturday, March 31, 2012 at 3:27pm
When the leading coefficient a is positive, the parabola opens up ( concave up )
For function:
x ^ 2  2 x  8
the leading coefficient is a = 1
function is concave up
When the parabola ia concawe up all walues between roots are negative.
No negative number can have a real square root.
Funtions zerro points are :
 2 and 4
So domain of your fuction:
(  infinity , 2 ] U [ 4 ,infinity )
OR
x <= 2 and x >= 4
If you don't knowe how to solve equation:
x ^ 2  2 x  8 = 0
In google type:
quadratic equation online
When you see list of results click on:
Free Online Quadratic Equation Solver:Solve by Quadratic Formula
When page be open in rectangle type:
x ^ 2  2 x  8 = 0
and click option: solve it!
You wil see solution stepbystep
If you want graph of functions:
Go on :
wolframalpha dot com
When page be open in rectangle type :
x ^ 2  2 x  8
and click option =
after few seconds yo will everythig about function
Then type :
sqrt ( x ^ 2  2 x  8 )
and click option =
P.S.
Sorry for My bad English